This silky matte glaze produces an appearance very similar to dolomite matte glazed ware fired in cone 10 reduction. The degree of matteness can be controlled by the cooling rate of the firing. Although this body is made by Standard Ceramics, the effect would be similar using speckled bodies made by other manufacturers also. These pieces made by Tom Friedman.
Before jumping to conclusions consider all the factors that relate. Such bodies contain only about 0.2% of 60-80 mesh manganese granular compared to many glazes that contain 5% powdered manganese (as a colorant). The vast majority of the metal particles are encapsulated within the clay matrix. The tiny percentage exposed at the body surface are under the glaze. What bleeds up through the glaze, to either near or at the surface, is not the particle itself. Rather, the particles dissolve partially and bleed out in all directions. The glaze stains in relation to the MnO concentration and its own melt fluidity. The transparency and thickness of the glaze either amplify or subdue the appearance of the specks. Thus, a food surface stained by manganese is not at all the same thing as raw melted manganese in contact with food. Consider also that total area of manganese-stained glass on a functional surface is extremely small. Notwithstanding all of this, there is a public perception of glaze toxicity that must be considered, some potters thus use engobes under the glaze on food surfaces, these limit the ability of the metal particles to diffuse.
G2934Y - Cone 6 Magnesia Matte Low LOI Version
The same chemistry as the widely used G2934 but the MgO is sourced from a frit and talc instead of dolomite. It has a finer surface, less cutlery marking and staining.
Sign up at the home page.